| |
VK2ZRG > SETI 06.12.04 15:43l 30 Lines 976 Bytes #999 (0) @ WW
BID : 979_VK2ZRG
Read: GUEST
Subj: Gain of Arecibo at 440 MHz
Path: DB0FHN<DB0MRW<DB0WUE<DK0WUE<DB0RES<ON0AR<7M3TJZ<ZL2TZE<VK5UJ<VK5BRC<
VK5ATB<VK2AAB<VK2WI
Sent: 041206/1030Z @:VK2WI.#SYD.NSW.AUS.OC #:55858 [SYDNEY] FBB7 $:979_VK2ZRG
From: VK2ZRG@VK2WI.#SYD.NSW.AUS.OC
To : SETI@WW
VK2ZRG/TPK 1.83d Msg #:979 Date:06-12-04 Time:10:27Z
R:041204/1939 @:WT3V.#CNJ.NJ.USA.NA #:31981 $:31981_WT3V
Hello again Warren,
It's nice to exchange bulletins with someone without getting
abuse. I got the gain figure for Arecibo at 1 GHz from the ARRL Antenna H/B.
Peak gain occurs around 800 MHz. The 440 MHz, 60 dB figure, was a quick, back
of an envelope calculation, assuming a perfect parabolic surface.
Here is a more detailed calc for 440 MHz.
Lambda = 300/440 = 0.6818 metres. Diameter = 305 metres.
(152.5 / 0.61818)^2 * Pi * 0.55 = 86444.7 square wavelengths.
Gain over isotropic = 86444.7 * 4 * Pi = 1086296
Gain in dB = 10 * log(1086296) = 60.4 dB.
The graph in the ARRL book for 432 MHz, shows around 58.8 dB gain.
The few dB difference is probably due to inaccuracies in the parabolic surface.
Merry Cricket, Ho Ho Ho
73s from Ralph VK2ZRG@VK2WI.#SYD.NSW.AUS.OC
/ack
Read previous mail | Read next mail
| |
